Abstract View of System Components

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Chapter 1: Introduction
пЃ® What is an Operating System?
пЃ® Mainframe Systems
пЃ® Desktop Systems
пЃ® Multiprocessor Systems
пЃ® Distributed Systems
пЃ® Clustered System
пЃ® Real -Time Systems
пЃ® Handheld Systems
пЃ® Computing Environments
Operating System Concepts
1.1
Silberschatz, Galvin and Gagne пѓ“2002
What is an Operating System?
пЃ® A program that acts as an intermediary between a user of
a computer and the computer hardware.
пЃ® Operating system goals:
пЃ† Execute user programs and make solving user problems
easier.
пЃ† Make the computer system convenient to use.
пЃ® Use the computer hardware in an efficient manner.
Operating System Concepts
1.2
Silberschatz, Galvin and Gagne пѓ“2002
Computer System Components
1. Hardware вЂ“ provides basic computing resources (CPU,
memory, I/O devices).
2. Operating system вЂ“ controls and coordinates the use of
the hardware among the various application programs for
the various users.
3. Applications programs вЂ“ define the ways in which the
system resources are used to solve the computing
problems of the users (compilers, database systems,
video games, business programs).
4. Users (people, machines, other computers).
Operating System Concepts
1.3
Silberschatz, Galvin and Gagne пѓ“2002
Abstract View of System Components
Operating System Concepts
1.4
Silberschatz, Galvin and Gagne пѓ“2002
Operating System Definitions
пЃ® Resource allocator вЂ“ manages and allocates resources.
пЃ® Control program вЂ“ controls the execution of user
programs and operations of I/O devices .
пЃ® Kernel вЂ“ the one program running at all times (all else
being application programs).
Operating System Concepts
1.5
Silberschatz, Galvin and Gagne пѓ“2002
Mainframe Systems
пЃ® Reduce setup time by batching similar jobs
пЃ® Automatic job sequencing вЂ“ automatically transfers
control from one job to another. First rudimentary
operating system.
пЃ® Resident monitor
пЃ† initial control in monitor
пЃ† control transfers to job
пЃ† when job completes control transfers pack to monitor
Operating System Concepts
1.6
Silberschatz, Galvin and Gagne пѓ“2002
Memory Layout for a Simple Batch System
Operating System Concepts
1.7
Silberschatz, Galvin and Gagne пѓ“2002
Multiprogrammed Batch Systems
Several jobs are kept in main memory at the same time, and the
CPU is multiplexed among them.
Operating System Concepts
1.8
Silberschatz, Galvin and Gagne пѓ“2002
OS Features Needed for Multiprogramming
пЃ® I/O routine supplied by the system.
пЃ® Memory management вЂ“ the system must allocate the
memory to several jobs.
пЃ® CPU scheduling вЂ“ the system must choose among
several jobs ready to run.
пЃ® Allocation of devices.
Operating System Concepts
1.9
Silberschatz, Galvin and Gagne пѓ“2002
Time-Sharing SystemsвЂ“Interactive Computing
пЃ® The CPU is multiplexed among several jobs that are kept
in memory and on disk (the CPU is allocated to a job only
if the job is in memory).
пЃ® A job swapped in and out of memory to the disk.
пЃ® On-line communication between the user and the system
is provided; when the operating system finishes the
execution of one command, it seeks the next вЂњcontrol
statementвЂќ from the userвЂ™s keyboard.
пЃ® On-line system must be available for users to access data
and code.
Operating System Concepts
1.10
Silberschatz, Galvin and Gagne пѓ“2002
Desktop Systems
пЃ® Personal computers вЂ“ computer system dedicated to a
пЃ®
пЃ®
пЃ®
пЃ®
single user.
I/O devices вЂ“ keyboards, mice, display screens, small
printers.
User convenience and responsiveness.
Can adopt technology developed for larger operating
systemвЂ™ often individuals have sole use of computer and
do not need advanced CPU utilization of protection
features.
May run several different types of operating systems
(Windows, MacOS, UNIX, Linux)
Operating System Concepts
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Silberschatz, Galvin and Gagne пѓ“2002
Parallel Systems
пЃ® Multiprocessor systems with more than on CPU in close
communication.
пЃ® Tightly coupled system вЂ“ processors share memory and a
clock; communication usually takes place through the
shared memory.
пЃ® Advantages of parallel system:
пЃ† Increased throughput
пЃ† Economical
пЃ† Increased reliability
пЂґ graceful degradation
пЂґ fail-soft systems
Operating System Concepts
1.12
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Parallel Systems (Cont.)
пЃ® Symmetric multiprocessing (SMP)
пЃ† Each processor runs and identical copy of the operating
system.
пЃ† Many processes can run at once without performance
deterioration.
пЃ† Most modern operating systems support SMP
пЃ® Asymmetric multiprocessing
пЃ† Each processor is assigned a specific task; master
processor schedules and allocated work to slave
processors.
пЃ† More common in extremely large systems
Operating System Concepts
1.13
Silberschatz, Galvin and Gagne пѓ“2002
Symmetric Multiprocessing Architecture
Operating System Concepts
1.14
Silberschatz, Galvin and Gagne пѓ“2002
Distributed Systems
пЃ® Distribute the computation among several physical
processors.
пЃ® Loosely coupled system вЂ“ each processor has its own
local memory; processors communicate with one another
through various communications lines, such as highspeed buses or telephone lines.
пЃ® Advantages of distributed systems.
пЃ† Resources Sharing
пЃ† Computation speed up вЂ“ load sharing
пЃ† Reliability
пЃ† Communications
Operating System Concepts
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Distributed Systems (cont)
пЃ® Requires networking infrastructure.
пЃ® Local area networks (LAN) or Wide area networks (WAN)
пЃ® May be either client-server or peer-to-peer systems.
Operating System Concepts
1.16
Silberschatz, Galvin and Gagne пѓ“2002
General Structure of Client-Server
Operating System Concepts
1.17
Silberschatz, Galvin and Gagne пѓ“2002
Clustered Systems
пЃ® Clustering allows two or more systems to share storage.
пЃ® Provides high reliability.
пЃ® Asymmetric clustering: one server runs the application
while other servers standby.
пЃ® Symmetric clustering: all N hosts are running the
application.
Operating System Concepts
1.18
Silberschatz, Galvin and Gagne пѓ“2002
Real-Time Systems
пЃ® Often used as a control device in a dedicated application
such as controlling scientific experiments, medical
imaging systems, industrial control systems, and some
display systems.
пЃ® Well-defined fixed-time constraints.
пЃ® Real-Time systems may be either hard or soft real-time.
Operating System Concepts
1.19
Silberschatz, Galvin and Gagne пѓ“2002
Real-Time Systems (Cont.)
пЃ® Hard real-time:
пЃ† Secondary storage limited or absent, data stored in short
term memory, or read-only memory (ROM)
пЃ† Conflicts with time-sharing systems, not supported by
general-purpose operating systems.
пЃ® Soft real-time
пЃ† Limited utility in industrial control of robotics
пЃ† Useful in applications (multimedia, virtual reality) requiring
advanced operating-system features.
Operating System Concepts
1.20
Silberschatz, Galvin and Gagne пѓ“2002
Handheld Systems
пЃ® Personal Digital Assistants (PDAs)
пЃ® Cellular telephones
пЃ® Issues:
пЃ† Limited memory
пЃ† Slow processors
пЃ† Small display screens.
Operating System Concepts
1.21
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Migration of Operating-System Concepts and Features
Operating System Concepts
1.22
Silberschatz, Galvin and Gagne пѓ“2002
Computing Environments
пЃ® Traditional computing
пЃ® Web-Based Computing
пЃ® Embedded Computing
Operating System Concepts
1.23
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